Fix TypeError: coroutine was expected, got None

- Replace async_create_task() calls with direct calls to async_write_ha_state()
- async_write_ha_state() is synchronous, not a coroutine
- Fixes issue reported in #54 comments where users got TypeError
- Updated both template_sensor_state_listener and template_sensor_startup callbacks

Author: pilotak

custom_components/attributes/sensor.py

@@ -263,7 +263,7 @@ async def async_added_to_hass(self):
         @callback
         def template_sensor_state_listener(event):
             """Handle device state changes."""
-            self.hass.async_create_task(self.async_write_ha_state())
+            self.async_write_ha_state()
 
         @callback
         def template_sensor_startup(event):
@@ -272,7 +272,7 @@ def template_sensor_startup(event):
                 self.hass, self._entity, template_sensor_state_listener
             )
 
-            self.hass.async_create_task(self.async_write_ha_state())
+            self.async_write_ha_state()
 
         self.hass.bus.async_listen_once(
             EVENT_HOMEASSISTANT_START, template_sensor_startup